It is known that in industrial environments a gas network is used with coupled networks at different pressures. The gas can be steam for example, but also compressed air, natural gas, nitrogen or another type of gas.
The pressure in a network is obtained through a balance between gas supply and gas consumption, which in turn is controlled by either compressing gas from a certain pressure to a higher pressure, by a ‘compression station’, or by expanding gas from a certain pressure to a lower pressure, by an ‘expansion station’. This expansion station can be a simple pressure reducing valve or an expander that converts the pressure difference into mechanical and/or electrical energy.
However, the known devices or machines only enable the gas to be processed in one direction: from high pressure to low pressure in pressure reducing valves and expanders or from low pressure to high pressure in compressors.
This has the disadvantage in the case of an expansion station that low pressure gas cannot be compressed to high pressure gas in the reverse direction, for example to flexibly respond to an increased gas demand in the high pressure network. Also a compression station cannot be used as an expansion station or flexibly respond to an increased demand in the low pressure network.
Traditionally gas networks with separate compression stations and separate expansion stations have the disadvantage that they cannot easily be deployed for energy storage.
As is known electrical energy cannot be stored directly, and it would be advantageous in times of a surplus of electrical energy if this could be used for compressing gas and using the gas network as an energy storage volume, and later expanding it back via an expander to generate electricity.
However, the traditional devices are unidirectional with regard to operation and cannot be used for this purpose.
It is then also often necessary to install two or more machines in the station, i.e. at least one expander and at least one compressor.
This has the disadvantage that the entire installation and control thereof becomes more complex and expensive.